The similarity between Stairway to Heaven and a song that members of Led Zeppelin are accused of copying can be found in music dating back 300 years, a court has heard.

Singer Robert Plant and guitarist Jimmy Page are facing trial in Los Angeles after they allegedly "lifted" the opening guitar riff on their 1971 hit from an instrumental track called Taurus by the American band Spirit.

A lawsuit has been filed by Michael Skidmore, the trustee of Spirit guitarist Randy Wolfe - known as Randy California - who drowned in 1997 having never taken legal action over the song.

Lawrence Ferrara, a music professor at New York University, said 17th century Venetian opera singers and Mozart used music techniques which feature in both Stairway To Heaven and Taurus as he played both songs on a keyboard in the courtroom.

He told the jury the only similarity between the two songs was a "common" descending sequence of notes.

"That progression, that movement, has been around for 300 years, dating back to the 17th century," he said. "In the 20th century, before Taurus, a large number of popular musicians, artists and composers also used it."

Mr Ferrara, an expert witness for Led Zeppelin's legal team, said the technique was a "musical building block" for a song.

"It was not something anyone can possibly own," he added. "It's not only what they did 300 years ago but what composers of all genres do."

Mr Ferrara said the rhythm of Stairway To Heaven and Taurus was "dramatically different" and he had found 20 pieces of music recorded before Spirit's song that also featured the same descending musical scale.

He said Johnny Mathis's 1960 hit My Funny Valentine, the opening of Michelle by The Beatles and the 1967 song Music To Watch Girls By all had similarities with the track Taurus.

The court heard Page and Plant earned tens of millions of dollars from Stairway To Heaven and other Led Zeppelin songs over the past five years.

Economist Michael Einhorn told jurors the musicians had received 58.5 million dollars (£40.68 million) from music sales, publishing rights and a record deal since May 2011.

Page, 72, has previously told the court he had not heard Taurus until his son-in-law showed him a comparison with Stairway To Heaven on the internet a few years ago.

He and Plant, 67, have sat next to each other in court during the copyright infringement trial, which is expected to conclude next week.